Assessing the role of redox partners in TthLPMO9G and its mutants: focus on H 2 O 2 production and interaction with cellulose.

Autor: Chorozian K; Industrial Biotechnology & Biocatalysis Group, School of Chemical Engineering, National Technical University of Athens, Zografou Campus, 15772, Athens, Greece., Karnaouri A; Laboratory of General and Agricultural Microbiology, Department of Crop Science, Agricultural University of Athens, 11855, Athens, Greece., Georgaki-Kondyli N; Industrial Biotechnology & Biocatalysis Group, School of Chemical Engineering, National Technical University of Athens, Zografou Campus, 15772, Athens, Greece., Karantonis A; Laboratory of Physical Chemistry and Applied Electrochemistry, School of Chemical Engineering, National Technical University of Athens, Zografou Campus, 15772, Athens, Greece., Topakas E; Industrial Biotechnology & Biocatalysis Group, School of Chemical Engineering, National Technical University of Athens, Zografou Campus, 15772, Athens, Greece. vtopakas@chemeng.ntua.gr.
Jazyk: angličtina
Zdroj: Biotechnology for biofuels and bioproducts [Biotechnol Biofuels Bioprod] 2024 Feb 01; Vol. 17 (1), pp. 19. Date of Electronic Publication: 2024 Feb 01.
DOI: 10.1186/s13068-024-02463-y
Abstrakt: Background: The field of enzymology has been profoundly transformed by the discovery of lytic polysaccharide monooxygenases (LPMOs). LPMOs hold a unique role in the natural breakdown of recalcitrant polymers like cellulose and chitin. They are characterized by a "histidine brace" in their active site, known to operate via an O 2 /H 2 O 2 mechanism and require an electron source for catalytic activity. Although significant research has been conducted in the field, the relationship between these enzymes, their electron donors, and H 2 O 2 production remains complex and multifaceted.
Results: This study examines TthLPMO9G activity, focusing on its interactions with various electron donors, H 2 O 2 , and cellulose substrate interactions. Moreover, the introduction of catalase effectively eliminates H 2 O 2 interference, enabling an accurate evaluation of each donor's efficacy based on electron delivery to the LPMO active site. The introduction of catalase enhances TthLPMO9G's catalytic efficiency, leading to increased cellulose oxidation. The current study provides deeper insights into specific point mutations, illuminating the crucial role of the second coordination sphere histidine at position 140. Significantly, the H140A mutation not only impacted the enzyme's ability to oxidize cellulose, but also altered its interaction with H 2 O 2 . This change was manifested in the observed decrease in both oxidase and peroxidase activities. Furthermore, the S28A substitution, selected for potential engagement within the His1-electron donor-cellulose interaction triad, displayed electron donor-dependent alterations in cellulose product patterns.
Conclusion: The interaction of an LPMO with H 2 O 2 , electron donors, and cellulose substrate, alongside the impact of catalase, offers deep insights into the intricate interactions occurring at the molecular level within the enzyme. Through rational alterations and substitutions that affect both the first and second coordination spheres of the active site, this study illuminates the enzyme's function. These insights enhance our understanding of the enzyme's mechanisms, providing valuable guidance for future research and potential applications in enzymology and biochemistry.
(© 2024. The Author(s).)
Databáze: MEDLINE
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